Ahmad Abu-Akel^1,2, Roy Ramati^1,3, Shaden Zein Aldeen^1,3, Yaffa Yeshurun^1,3; ¹School of Psychological Sciences, University of Haifa, ²The Haifa Brain and Behavior Hub (HBB), University of Haifa, ³The Institute of Information Processing and Decision Making, University of Haifa

Early perceptual processes provide a crucial foundation for understanding the intersection of autism and psychosis spectrum disorders (ASD and PSD, respectively), offering insights into shared and distinct mechanisms across these dimensions. We report findings from two complementary studies examining early- and mid-level perceptual processing in neurotypical adults, assessing autistic traits and psychosis proneness in tandem. The first study investigates magno-like and parvo-like processing, previously implicated in both ASD and PSD, using the pulsed- and steady-pedestal paradigms combined with luminance contrast discrimination. The second study focuses on temporal crowding, a phenomenon reflecting long-lasting inter-item temporal interference. Three-item sequences were presented centrally with varying SOA (200–400ms); the task required estimating the middle item’s orientation and the errors were analyzed using a mixture-modeling approach. Together, these studies explore key perceptual aspects relevant to ASD and PSD while advancing our understanding of perceptual processes within the occipital lobe along a gradient of increasing complexity. Results from polynomial regression with response surface analysis in Study 1 (N=81) found no association between autistic traits or psychosis proneness and parvo-like or magno-like processing. Similar analyses in Study 2 assessed the relationship between autistic traits, psychosis proneness, and temporal crowding (SOA modifications of the model parameters). In the difficult version (N=82), greater bias toward autistic traits corresponded to a larger reduction in guessing rates with longer SOAs, while substitution errors with the preceding distractor decreased in participants with balanced autistic traits and psychosis proneness (e.g., high tendencies on both). In the easier version (N=94), where stimuli were more discernible, we observed a similar reduction in substitution errors for ‘balanced’ participants with the succeeding distractor. These findings highlight nuanced, task-dependent interactions between autistic traits and psychosis proneness, suggesting that balanced trait dimensions may optimize certain perceptual processes, with implications for understanding sensory integration deficits in ASD and PSD.